Thursday, October 26, 2017

Anti-Vaxxers, climate change deniers rejoice

Aside from inflicting devastating natural disasters on often
vulnerable communities, climate change can also spur outbreaks of infectious
diseases like Zika , malaria and dengue fever, according to a new study by
researchers at the University of Colorado Anschutz Medical Campus.

"Climate
change presents complex and wide-reaching threats to human health," said
Cecilia Sorensen, MD, lead author of the study and the Living Closer Foundation
Fellow in Climate and Health Policy at CU Anschutz. "It can amplify and
unmask ecological and socio-political weaknesses and increase the risk of
adverse health outcomes in socially vulnerable regions."

When
natural disasters strike such places, she said, the climatic conditions may
make the public health crisis significantly worse.

The
researchers said these vulnerabilities can happen anywhere. After Hurricane
Katrina hit New Orleans, cases of West Nile disease doubled the next year. Climate change in Africa appears to be increasing cases of malaria. And the
recent destruction in Houston, Florida and Puerto Rico due to hurricanes may
usher in more infectious diseases in the years ahead.

The
study focused specifically on a magnitude 7.7 earthquake that struck coastal
Ecuador in April 2016, coinciding with an exceptionally strong El Niño event.
El Niños are associated with heavy rainfall and warmer air temperatures. They
are also linked to outbreaks of dengue fever.

Sorensen,
a clinical instructor in emergency medicine at CU Anschutz, was in Ecuador with
her co-authors working with the Walking Palms Global Initiative. They were
operating a mobile health clinic after the disaster.

"We
were seeing all of these viral symptoms in the wake of the quake," she
said. "We noticed a huge spike in Zika cases where the earthquake
occurred. Prior to this, there were only a handful of Zika cases in the whole
country." In fact, the researchers found the number of Zika cases had
increased 12-fold in the quake zone.

Zika
virus is transmitted by mosquitos. Symptoms are usually mild but the infection
can cause major abnormalities and even death in a developing fetus.

Warmer
temperatures and increased rainfall from the El Niño, along with a devastated
infrastructure and an influx of people into larger cities, likely caused the
spike in Zika cases, Sorensen said.

"We
saw so many people affected by the earthquake that were sleeping outside
without any shelter from mosquitoes, so we were worrying that the region's
changing climate could facilitate the spread of diseases," she said.
"Natural disasters can create a niche for emerging diseases to come out
and affect more people."

Sorensen's
team reviewed the existing research on the link between short-term climate
changes and disease transmission. They applied those findings to explain the
role of the earthquake and El Niño in the Zika outbreak.

The
researchers suggest El Niño created ideal conditions for Zika-carrying
mosquitos to breed and make more copies of the Zika virus. The warmer
temperatures and increased rainfall from El Niño have previously been associated
with a higher likelihood of dengue outbreaks. Warmer temperatures can also
accelerate viral replication in mosquitoes and influence mosquitos' development
and breeding habits.

At
the same time, the El Niño event brought warmer sea-surface temperatures, which
have been shown to correlate with outbreaks of mosquito-transmitted diseases.
Estimates from remote sensing data in coastal Ecuador show that sea-surface
temperatures were higher than average from 2014-2016.

The
team also believes an increase in water scarcity after the earthquake
indirectly benefited mosquito development. The quake damaged municipal water
systems, forcing people to store water in open containers outside their homes.
These served as additional habitats for mosquito larvae.

The
new findings could be used by governments to identify and protect vulnerable
communities before natural disasters happen, Sorensen said.

"One
idea is to develop disease models that can use existing climate models to predict
where these vectors will show up due to climate variability," she said.
"Applying these new models to areas that have pre-existing social
vulnerabilities could identify susceptible regions, allowing us to direct
healthcare resources there ahead of time."